1. Field of the Invention
The present invention relates generally to coaxial connectors for securing devices such as coaxial cables to connectors of equipment boxes or other coaxial components, and more particularly, to an improved coaxial connector that permits two mating connectors to be screwed together, or unscrewed from each other, without requiring that the main body of either connector be rotated.
2. Description of the Related Art
The cable television (CATV) industry within the United States, through the organization known as The Society of Cable Telecommunications Engineers, Inc. (SCTE) of Exton, Pa., has long since standardized on a Radio Frequency Coaxial Connector Interface known as the xe2x80x9cKSxe2x80x9d interface for use in trunk and distribution applications for CATV and high speed digital signals. These xe2x80x9cKSxe2x80x9d interface connectors are typically used to attach the end of a coaxial cable to a port on an amplifier housing, or other similar equipment. However, the xe2x80x9cKSxe2x80x9d interface is subject to several problems. Chief among these problems is that the SCTE xe2x80x9cKSxe2x80x9d interface specifications make no provision for a coupling apparatus or coupling method that could allow two mating connectors to be screwed together, or unscrewed from each other, without rotating one of the two connector bodies.
The most common method for dealing with this problem is to use a two-piece connector, or three-piece connector, that includes at least a so-called front body and a rear body; an example of such a connector is shown in U.S. Pat. No. 4,854,893, owned by the assignee of the present invention. The ""893 patent discloses a two-piece coaxial cable connector wherein the rear nut body is engaged over the exposed end of a coaxial cable and engages the outer conductor of the coaxial cable. The front nut body includes a center pin that seizes the center conductor of the coaxial cable as the front nut body is tightened over the rear nut body. When disconnecting such a two-piece connector from an internally-threaded port of an equipment box, the two-piece connector must first be disassembled from the coaxial cable, so that the front nut body may be unscrewed from the equipment housing without twisting the coaxial cable. This is obviously more complicated and time consuming than simply unscrewing a coupling nut, as is the case with most other types of coaxial connectors.
In many cases, it would be highly desirable to allow the mating of two connectors without the need to disassemble either connector, and without the need to rotating either connector body. For example, in the case of a factory-made jumper cable assembly, equipped with coaxial connectors at each end of such cable, the end connectors cannot be removed from the cable assembly, and it would be impossible to mate such a jumper to two fixed pieces of equipment without somehow disassembling one or both of such end connectors. The nature of the standardized KS interface precludes the use of a simple rotatable coupling nut from being used to secure the connectors to mating ports because the coupling nut would xe2x80x9cbottom-outxe2x80x9d before the main body of the connector xe2x80x9cbottoms-outxe2x80x9d; this would leave the main body of the connector loose, and without a proper electrical ground connection. Moreover, the standardized xe2x80x9cKSxe2x80x9d interface is dimensionally incomplete, and accordingly allows a wide range of dimensions that can cause compatibility problems between various manufacturers.
The most common approach toward dealing with the above-described problem is to use a coupling nut in conjunction with a jam nut. The coupling nut is first tightened against the equipment housing; then, the jam nut is tightened against the coupling nut in order to take up any slack between the coupling nut and connector body. It is usually necessary to form wrench flats on the connector body for allowing an installer to apply a wrench to the connector body to prevent it from rotating while the coupling nut and jam nut are being tightened. However, the need to apply wrenches to the coupling nut, jam nut, and connector body presents an awkward and confusing situation, and one that is prone to error. For example, it is not uncommon for an installer to tighten the nuts is the wrong order, or to have one nut loosen while the other is being tightened. The end result is loose connections in the field.
In addition, prior art seizing mechanisms, used within female coaxial connectors to seize the central conductor of the male connector, rely upon the distance that the front, male body of the coaxial connector protrudes into the rear, female body to activate the seizing mechanism. The SCTE interface specifications allows this distance to vary from 0.290xe2x80x3 to 0.370xe2x80x3, and this permitted variation distance is too large to ensure consistent performance of any seizing mechanism that relies upon this dimension. Moreover, such seizing mechanisms within female connectors typically have sharp edges which can rub against, and damage, the protective coating ordinarily plated upon the center conductor of the male connector if the seizing mechanism and center conductor are allowed to rotate with respect to one another during tightening of the male connector to the female connector.
Accordingly, it is an object of the present invention to provide a coaxial connector for connecting the end of a coaxial member to a mating component wherein the two mating connectors can be coupled together, or uncoupled from each other, without requiring that the main body of either connector be rotated.
Another object of the present invention is to provide such a coaxial connector that avoids the need for disassembly of two or more pieces of the connector from a coaxial cable in order to disengage the connector from the mating component.
Still another object of the present invention is to provide such a coaxial connector that is relatively easy to use and inexpensive to manufacture.
Yet another object of the present invention is to provide such a coaxial connector that can be coupled with a mating component by a field technician in a relatively quick manner.
A further object of the present invention is to provide such a coaxial connector that is relatively insensitive to the wide dimensional variations allowed by the SCTE interface specifications, thereby assuring the compatibility of such coaxial connectors with mating components produced by various other manufacturers.
A still further object of the present invention is to provide such a coaxial connector that can be securely tightened in a simple manner akin to the tightening of a conventional coupling nut, but which may also include an internal actuating mechanism, actuated during the tightening process, to accomplish additional desired functions, such as seizing the center conductor of the mating connector with great force.
Another object of the present invention is to provide such a connector that can form a weather-tight seal, while avoiding any significant drag on any rotatable components until the rotatable component approaches its fully mated condition, thereby allowing such connector to be quickly hand tightened initially, and requiring a wrench only for the last few turns.
Yet another object of the present invention is to provide such a coaxial connector which enhances the reliability and stability of the connector by providing low and stable contact resistance and preventing any mechanical movement as between the coaxial connector and the coaxial conductors joined thereto.
An additional object of the present invention is to prevent any relative rotation as between the center conductor/center contact mechanism that electrically joins the coaxial connector and its mating coaxial component as the outer conductor of the coaxial conductor is tightened onto the outer conductor of its mating component, thereby avoiding damage to the plating applied to such center conductor/center contact mechanism that might otherwise result when sharp edges of the center contact mechanism rub against the coating plated upon the center conductor.
These and other objects of the present invention will become more apparent to those skilled in the art as the description of the present invention proceeds.
Briefly described, and in accordance with a preferred embodiment thereof, the present invention relates to a coaxial connector used to connect the end of a coaxial member, such as a coaxial cable, to a mating component, and including a front body, a rear body rotatably secured the front body, a center conductor extending within the front body, and a nut that surrounds the front body and is secured thereto in such manner that it can slide axially relative to the front body, but it is substantially locked against rotation relative to the front body.
The front body includes a central bore and extends between first and second opposing ends along a longitudinal axis; the first end of the front body has a threaded surface for engaging a mating threaded component. This threaded surface can be formed upon an external surface of the first end of the front body for mating with a female connector; alternatively, this threaded surface can be formed upon an internal surface of the first end of the front body for mating with male connector.
The rear body includes a central bore coaxial with the longitudinal axis of the front body; a first end of the rear body surrounds the second end of the front body.and is rotatably secured thereto in a manner which allows the front body to be movable, relative to the rear body, along the longitudinal axis between retracted and extended positions. Preferably, this coupling is effected by a retaining ring extending within an annular recess formed in the central bore of the rear body proximate its first end, and further extending within an annular recess formed within the external surface of the front body proximate the second end thereof. The second end of the rear body is adapted to engage a coaxial member, e.g., the end of a coaxial cable.
A center conductor is supported within the central bore of the front body along its longitudinal axis, and further extends within the central bore of the rear body. This center conductor is adapted to electrically and mechanically couple a center conductor of the coaxial member (e.g., the center wire of a coaxial cable) to a center conductor of the aforementioned mating component (e.g., a mating connector). Preferably, a supporting insulator is included in the central bore of the front body to help support such center conductor, while permitting the front body to rotate about, and move along, the longitudinal axis of the center conductor.
In the case where the first end of the front body is internally threaded for receiving a male mating connector having a male center conductive pin, a first end of the female center contact preferably includes a slotted bore for receiving such male pin. In this example, the second end of the female center contact is preferably anchored within the central bore of the rear body, as by an anchoring insulator secured within the central bore of the rear body. The aforementioned supporting insulator has a central bore extending coaxially with the longitudinal axis of the front body for receiving the first end of the female center contact and for allowing the male pin to be inserted therein. Preferably, the central bore of the supporting insulator includes a tapered wall for radially compressing the slotted end of the female center contact as the front body and rear body move axially apart from each other, thereby capturing the male pin in the slotted bore of the female center contact.
The nut has a central aperture defined by an internal surface, and the front body extends through this central aperture. The internal surface of the nut engages the external surface of the front body in a manner which prevents substantial rotation of the nut relative thereto, while permitting the nut to slide axially along the front body relative to the longitudinal axis thereof. The nut includes first and second opposing side walls, and the first side wall is adapted to slidingly engage and abut the mating component to which the first end of the front body is to be secured. The opposing second side wall of the nut is adapted to slidingly engage and abut the first end of the rear body. Thus, as the threaded region at the first end of the front body is threadedly engaged with the mating component (e.g., a mating connector), the nut bears against the first end of the rear body and pushes the rear body away from the front body along the aforementioned longitudinal axis.
Preferably, an O-ring is disposed between the second end of the front body and the central bore of the rear body to form a seal therebetween. As the nut forces the rear body toward its extended position away from the front body, the O-ring is compressed to form a seal between the second end of the front body and the first end of the rear body. If desired, a second O-ring can be included within or upon the first end of the front body to form a seal with the aforementioned mating component (e.g., a mating connector). In the case where the first end of the front body is externally threaded, the central aperture of the nut preferably extends over and around such second O-ring before the front body is mated with the mating component.
The present invention also relates to a method of assembling a coaxial connector of the type described above. The method includes the step of providing a front body having first and second opposing ends and having a central bore extending along a longitudinal axis; as described above, the first end of the front body has a threaded region for threadedly engaging a mating threaded component. The second end of the front body has an external surface that initially tapers outwardly to a peak and then tapers back inwardly. The method also includes the step of providing a rear body having first and second opposing ends and having a central bore coaxial with the longitudinal axis of the front body. The first end of the rear body is adapted to receive the second end of the front body; the second end of the rear body is adapted to receive a coaxial conductor. The rear body includes an annular O-ring recess formed within the central bore thereof The method includes the further step of disposing a center conductor within the central bore of the front body along its longitudinal axis. In addition, an O-ring is inserted into the annular O-ring recess of the rear body.
In practicing the foregoing method, the second end of the front body is inserted into the first end of rear body until the peak of the front body engages the O-ring; thereafter, one continues to insert the second end of the front body into the first end of the rear body, while allowing the peak to compress the O-ring into the annular O-ring recess of the rear body as the peak passes the O-ring. One continues to advance the second end of the front body into the first end of the rear body, allowing the peak to clear the O-ring.
The above-described method preferably includes the additional step of rotatably securing the front body to the rear body by forming an annular recess on an external surface of the front body, forming an annular retaining ring recess within the central bore of the rear body, inserting a compressible retaining ring into the annular recess of the front body, and advancing the second end of the front body into the first end of the rear body until the retaining ring expands into the annular retaining ring recess of the rear body. Ideally, the annular retaining ring recess of the rear body is formed to be wider than the thickness of the retaining ring for allowing the front body and rear body to slide axially with respect to each other.
The above-described method may optionally include the additional steps of providing a nut having a central aperture defined by an internal surface, sliding the nut over the second end of the front body before the second end of the front body is inserted into the first end of rear body, and engaging the internal surface of the nut with the external surface of the front body to prevent substantial rotation of the nut relative to the front body, while permitting the nut to be axially slidable along the front body relative to the longitudinal axis of the front body.